Abstracts (complete list) - Wissenschaft Online

Mario Zaiss, Jochen Zwerina, Karin Polzer, Eva Gückel, Alla Skapenko, Hendrick
Schulze-Koops, Nikki Horwood, Andrew Cope, Georg Schett
Regulatory T cells suppress osteoclast formation- a new link
between the immune system and bone
Objective.
To investigate whether regulatory T cells can suppress osteoclast differentiation
and to define a new potential link between the immune system and the skeleton.
Methods.
Regulatory CD4+CD25+foxp3+ T cells were isolated and purified from the spleen and
co-cultured with CD11b+ osteoclast precursor cells isolated from the bone marrow.
Osteoclastogenesis and bone erosion was assessed by TRAP staining and pit resorption
assay, respectively. In addition, trans-well experiments and cytokine blocking
experiments were performed to define the mechanisms of interaction between
regulatory T cells and osteoclasts.
Results.
CD4+CD25+foxp3+ T cells dose dependently inhibited MCSF- and RANKL dependent
osteoclast formation in contrast to CD4+CD25- T cells. Also pit formation was inhibited
by up to 80%. The blockade of osteoclast formation was not based on an alteration of
RANKL/OPG balance but essentially dependent on direct cell-cell contact via CTLA-4.
Regulatory T cell-mediated expression of TGF-β, IL-4 and IL-10 contributed to the
inhibitory effect on osteoclastogenesis, but was not essential.
Conclusion.
These data show that CD4+CD25+foxp3+ regulatory T cells suppress osteoclast
formation. These data provide a new link between the immune system and bone and
extend our knowledge on the regulation of bone homeostasis by the immune system.